1. Field of the Invention
The present invention relates to integrated circuit (IC) manufacture and more particularly to an apparatus and method to remove organic matter contamination and particulate contamination from a photomask or reticle and a pellicle and to control electrostatic discharge (ESD) through in-situ application of ultraviolet light radiation during semiconductor manufacture.
2. Description of Related Art
Integrated circuits are generally made by photolithographic processes that use photomasks or reticles and an associated light source to project a circuit image on the surface of a silicon wafer or substrate. A photomask or reticle is generally a transparent ceramic substrate that is coated with a metallic layer forming a pattern for an electronic circuit. A pellicle is typically used to seal the photomask or reticle, isolating and protecting the reticle surface from particulate contamination and eliminating dust or other particles from the focal plane of the reticle pattern during the manufacture of integrated circuits.
In order to produce functioning integrated circuits at a high yield rate, the reticle and pellicle need to be free of defects that typically occur during integrated circuit (IC) manufacture, and specifically during processing and or handling of the reticle and pellicle. One such defect is organic/molecular contamination of the reticle surface. Surface molecular contamination, such as chemical stains or residues, on the surface of the reticle reduces and degrades the transmittance property and/or characteristic of the reticle, ultimately impacting the quality of the semiconductor device manufactured.
Another concern or defect affecting the quality of integrated circuits during the photolithography process is particulate contamination of the reticle. Particulate contamination may include any small particles, such as dust particles, that may be caught between the reticle mask and pellicle when affixing the two together. Particulate contamination may cause the photolithographic pattern transmitted on the wafer to change, distort, alter, etc. from its intended design, ultimately impacting the quality of the semiconductor device manufactured.
Another concern or defect affecting the quality of integrated circuits during the photolithography process is electrostatic discharge-induced defects or effects. In the semiconductor device manufacture, static electricity or electrostatic discharge (ESD) frequently develops on reticle surfaces or other surfaces made of insulating materials when they are touched or rubbed by other insulating materials. The electricity is produced based on a triboelectricity theory. The discharge of the static electricity can cause damages to semiconductor device as well as process tools. Furthermore, when electrostatic discharge (ESD) occurs after the assembly of pellicle to reticle, particulate contamination may be produced and affixed to the pellicle/reticle. This causes the photolithographic pattern transmitted on the wafer to distort from its intended design, ultimately impacting the quality of the semiconductor manufactured.